As output control apparatus for an engine mounted on a vehicle such as an automobile, those referred to as "Drive-By-Wire" systems, have been developed and are finding actual utility.
In general, they are of the type that the depressed position of an accelerator pedal (the amount of operation of the accelerator pedal) is detected without mechanically connecting the accelerator pedal to a throttle valve, a target drive shaft torque is determined from the position thus detected, and the throttle valve is driven by a motor so as to obtain such a target drive shaft torque.
According to the drive-by-wire system, the degree of opening of the throttle valve can be controlled based not only on the amount of operation of the accelerator pedal but also on various other data and hence the control of the output of the engine can be practiced from various facets.
Application examples of the drive-by-wire system include control for bringing the relation between the operation of the accelerator pedal and the output of the engine into conformity with given conditions determined in view of the driver's feeling and the movement of the vehicle, that is, so-called throttle-by-wire control.
In addition, there is also traction control wherein whenever a slip occurs at a wheel, the degree of opening of the throttle valve is reduced in spite of the depressed accelerator pedal to thereby cease the slip.
Also included is auto-cruise control which allows to maintain a desired speed even while accelerator pedal is at the released position.
It will therefore be convenient if all the three kinds of controls, i.e., the throttle-by-wire control, the traction control and the auto-cruise control would be successfully performed by a single unit of drive-by-wire system.
It is however the throttle valve that serves as a final operation means for each control. Moreover, only one throttle valve is generally provided. Practice of all the above controls by such a single unit is therefore accompanied by the problem that the control of the opening degree of the throttle valve becomes complex.
With the foregoing in view, this invention has as a principal object thereby the provision of control apparatus of the type that accelerator-by-wire control, traction control system and auto-cruise control can all be performed by the apparatus without complication of the controls.